Ignition system



1955 o. M. KURITZA ETAL 3,203,412

IGNITION SYSTEM Filed Jan. '7, 1963 V 2 Sheets-Sheet l INTER/VAL F I G 1COMBUSTION ENG/NE INVENTORS OLE/1' M. KUR/TZA BY EDWARD ll HAVEL mlu m J47775 1955 0. M. KURITZA ETAL 3 ,203,412

IGNITION SYSTEM 2 Sheets-Sheet 2 Filed Jan. 7, 1965 r0 DISTRIBUTOR OU/Sffi/BUTOR INVENTOR.

OLEH M KUH/TZ/I EDWARD ll HAVE].

BY W AUYS.

United States Patent 07 3,203,412 IGNITIGN SYSTEM (lleh M. Kuritza andEdward V. Havel, Chicago, Ill., assignors to Motorola, lino, FranklinPark, 111, a corporation of Illinois Filed Jan. 7, 1963, Ser. No.249,952 8 Claims. (Cl. 123-148) This application is acontinuation-in-part of application Serial No. 101,151, filed April 6,1961, now abandoned.

This invention relates generally to ignition systems for internalcombustion engines, and more particularly to an ignition systemincluding transistors for providing high voltage pulses from a lowvoltage electrical system.

Internal combustion engines as used in automobiles, trucks, etc.,include an ignition system controlled by contact points which make andbreak a circuit so that pulses are developed in a coil or transformer.The pulses from the coil are applied through a distributor to thevarious spark plugs or ignition means of the cylinders of the engine.The distributor and contact points are controlled by a timing systemwhich operates in synchronisrn with the engine itself. Such systems havethe disadvantage that in order to provide the high voltage required forignition, it is necessary that a substantial current be supplied to thecoil. When this current is interrupted through the contact points arcingtakes place and this is effective to pit the contacts. This results inpoor operation and requires that the points be replaced. Further, insuch systems the condenser used with the coil to provide the highvoltage pulse may also have to be frequently replaced.

It has been proposed to use ignition systems including transistors toeither replace the contact points or to permit reduced current throughthe contact points. However, such circuits have not been entirelysatisfactory for various reasons, one of which has been that thetransistor circuits have been expensive and have not provided reliableoperation under all conditions. In many transistor circuits thetransistor coupled to the coil is normally conducting and there has beena tendency for the coil to burn out.

It is therefore an object of the present invention to provide animproved ignition system for internal combustion engine.

Another object of the invention is to provide an ignition system for aninternal combustion engine which does not require the use of contactpoints for interrupting a circuit.

A further object of the invention is to provide a transistor ignitionsystem which is excited by a magnetic pulse producing device.

A feature of the invention is the provision of an ignition system for aninternal combustion engine including a pulsing unit for intermittentlycutting off a normally conducting transistor stage, and which producespulses to control a second transistor stage which applies pulses to astep-up transformer which provides the high voltage for ignition. Thepulsing unit may include a rotating member which moves with respect topole pieces to produce a voltage wave in a coil on the pole pieces.

Another feature of the invention is the provision of a transistorizedignition system including a first transistor stage which applies voltagepulses to a second non-conducting transistor stage which is renderedconducting and then cut off so that sharp pulses are produced which arestepped up in a transformer to produce high voltage for ignition.

A further feature of the invention is the pro-vision of an ignitionsystem including a transistor for applying voltage pulses to astep-transformer and which is normally non- .conducting so that thetendency of the transformer to 32%,412 Patented Aug. 31, 1965 burn outis reduced, with the transistor being intermittently rendered conductingto produce high voltage pulses in the transformer.

Still another feature of the invention is the provision of atransistorized ignition system having an interstage transformer couplinga driver transistor to the output transistor, wherein the interstagetransformer applies reverse bias to the output transistor during theperiod of high reverse voltage in the high voltage transformer so thatthe output transistor has improved voltage breakdown characteristics,and can withstand the reverse voltage applied thereto.

The invention is illustrated in the accompanying drawing wherein:

FIG. 1 illustrates one form of the ignition system in accordance withthe invention;

FIG. 2 shows the pulsing unit in a different position;

FIG. 3 includes curves showing the operation of the system of FIG. 1 atrelatively high speeds;

FIG. 4 is an enlarged view illustrating an alternate construction forthe pulsing unit; and

FIGS. 5 and 6 illustrate alternate forms of the circuit.

In practicing the invention there is provided an ignition system for aninternal combustion engine including a first stage having a transistorwhich is biased to be normally conducting. A magnetic pulsing unit isprovided including a magnet structure with a permanent magnet and a coilthrough which fiuX is passed and which is connected to the baseelectrode of the transistor. A rotary magnetic disc having projectionsis mounted so that the projections move adjacent to pole pieces of themagnetic structure so that pulses are produced in the coil. These pulsescause the transistor stage to be intermittently cut off so that a pulsewave is produced in the collector circuit thereof. The collector of thefirst transistor is coupled to the base of a second transistor, which isbiased to be normally cut off. The second transistor is renderedconducting by the pulses from the first transistor and then cut off sothat pulses are developed at the collector thereof and applied to theprimary of a step-up transformer. The secondary winding of the step-uptransformer is connected to the distributor to produce high voltagepulses therein. The coupling between the first and second transistors isprovided by a transformer which applies a reverse bias to the secondtransistor to improve its breakdown characteristics. The magneticstructure may be mounted to be advanced or retarded with respect to therotating disc to thereby control the timing of the pulses applied to thedistributor. The magnetic structure may take various different forms.The circuits of the transistor stages may take other forms and theoutput may be derived from the emitter electrode rather than thecollector electrode as described.

Referring now to the drawings, the ignition system is illustrated inFIG. 1 for use in an internal combustion engine 10 having a plurality ofcylinders which are fired by signals applied to terminals 11. The engineis mechanically connected to a distributor 12 which selectively applieshigh voltage pulses to the terminals 11. The distributor thereforeoperates at any time that the engine is turning over, either whenoperating on its own power or when being cranked by a starter or thelike.

The pulsing unit of FIG. 1 includes a permanent magnet 14 having polepieces 15 connected thereto, about Which are positioned coils 16. Thetwo coils 16 are connected in series to provide pulses to transistor 20as will be explained. The permanent magnet and coil assembly are mountedon a plate 17 which may be of the form used to support the contacts instandard automotive distributors. A toothed magnetic disc or wheel 18 ismounted for rotation so that the teeth 19 thereof pass by, and in closeproximity to, the ends of the pole pieces 15. The disc may be mounted onthe shaft which normally carries a cam to operate contact points instandard ignition systems. The disc 18 therefore rotates with thedistributor 12.

As stated above, the coils 16 are connected in a circuit to providepulses to the input of transistor 20. The coils 16 are connected inseries with resistor 22 between the emitter and base electrodes oftransistor 20. Bias potential is applied to the emitter electrode oftransistor from .the bias supply line 21, and through the voltagedivider circuit including resistor 22, coils 16 and resistor 23 to thebase electrode to this transistor. This bias potential causes thetransistor 20 to be normally conducting.

The resistor 23 may be a positive temperature coelficient thermistor tohold the output of the system substantially constant over a range oftemperature. Without this temperature compensation the high voltageproduced by the system falls off at both extremely high and extremelylow temperatures. The thermistor may have a linear characteristic whichprovides an increase in resistance of 36% per degree C. increase intemperature.

The collector electrode of transistor 20 is connected to transformer 25which applies the pulses from the tran sistor 23 to the transistor 23.Bias is applied to transistor 28 from line 21 to the emitter electrodethereof and through the secondary winding of transformer 25 to the baseelectrode. Transistor 28 is normally non-conducting, and is renderedconducting by the pulse applied between the base and emitter electrodethereof. Transistor 28 is cut off at the end of the pulse to develop asharp pulse in primary winding 31 of transformer 32. This pulse isstepped up in the secondary winding 33 of transformer 32, a pulse isapplied to the moving contactor 34 of the distributor. The pulse isthereby selectively applied to the terminals 11 of the cylinders of theinternal combustion engine.

The potential supply line 21 is connected to the electrical system ofthe vehicle in which the engine is used through terminals 35 and 36.Terminal 35 connects the line directly to the vehicle voltage source andis used during starting to provide maximum ignition voltage. Terminal 36connects line 21 to the electrical system through resistor 37 whichcauses a drop in the voltage, and the connection may be used after theengine has started.

It will be apparent from FIG. 1 that when the toothed wheel 18 is in theposition wherein teeth 19 thereof are directly aligned with the polepieces 15, maximum flux will be provided through the coils 16 by thepermanent magnet 14. When the toothed wheel is positioned so that atooth 19 thereof is between the ends of the pole pieces 15, as shown inFIG. 2, the flux through the coils will be minimum. This change in fluxthrough the coils 16 as the disc 18 rotates will develop a voltageacross the coils 16 as shown by curve A of FIG. 3. Because of theconduction of the transistor base-emitter diode action the voltageapplied between the base and emitter will not rise during the first halfof the cycle, but the negative portion of the cycle of curve A willcause the transistor 20 to be cut off. Curve B of FIG. 3 shows theVoltage at the emitter of transistor 20 with respect to the basethereof.

The voltage between the collector of transistor 20 and ground, which isapplied to transformer 25, is shown by curve C of FIG. 3. This voltagewill be positive when the transistor conducts and will swing negativewhen the transistor is cut oif. The negative swing of the voltage acrossthe primary winding of transformer 25 will peak first and then tend toreturn to zero, an inherent characteristic of transformer action. Theresultant change in current through the primary winding with respect totime induces a voltage in the secondary winding. This voltage is appliedbetween the base and emitter electrodes of transistor 28, and the waveform is shown by curve D of FIG. 3. As previously stated, transistor 28is normally non-conducting. However, the voltage applied between thebase and emitter electrodes thereof during the second half of the cyclewill cause the transistor 28 to conduct. The voltage at the collector oftransistor 28 is shown by curve E of FIG. 3. The pulse applied totransistor 28 causes the transistor to be driven first to saturation andthen back to cut off, to provide a sharp pulse in the primary winding 31of transformer 32. This is indicated at 4-0 on curve E. This pulse isstepped up in the transformer 32 to provide an extremely high voltage atthe movable contact 34 of the distributor 12.

During the period when transistor 20 is turned off, the decaying currentin the primary winding of transformer 25 induces a voltage in thesecondary winding thereof as shown in curve D. As transistor 20 isturned back on, the collapsing field in the secondary winding oftransformer 25 drives transistor 28 to cut off. The voltage in thesecondary winding resulting from this collapse, indicated at 39 in curveD, drives transistor 28 beyond cut off. This not only insures a rapidswitching action, but enables transistor 28 to withstand higher reversevoltage spikes developed in transformer 32. Because of the high voltagesnecessary for satisfactory firing of the spark plugs 11, transformer 32must be constructed so that a large voltage spike is induced insecondary winding 33 when transistor 28 is cut off and the field in thetransformer collapses. The rapid cut off of transistor 28, fromsaturation to reverse bias, aids in attaining such a large voltagespike. This large voltage spike produced in the secondary winding isaccompanied by a high voltage spike in the primary winding 31 which isapplied across the collector and emitter electrodes of transistor 28.

By applying reverse bias between the base and emitter electrodes oftransistor 28 at the same time that the high voltage spike is presentacross the collector and emitter electrodes, the breakdown capability oftransistor 28 is substantially increased. The interstage transformer 25supplies such reverse bias to transistor 28 to drive it into the BVcexregion. With proper interstage transformer design to insure maximumreverse bias, transistor 28 operating in the BVcex region is drivensufficiently beyond cut off .to withstand the maximum breakdown voltage.The transformer 25 applies this reverse bias of proper magnitude at thecritical time, enabling the transistor 28 to withstand the voltageapplied thereto from winding 31. This BVcex region, as is known to thoseskilled in the art, is the region of high transistor collector breakdowncapability when reverse bias is applied across the base and emitterelectrodes thereof.

The plate 17 of the pulsing unit, on which the coils 16 are mounted, iscommonly called the advance plate of the distributor and may be advancedor retarded with respect to the rotating disc 18. This operation isgenerally the same as the movement of the contact points so that thespark is advanced or retarded in ignition systems presently used. Thiscontrols the time of firing of each cylinder with respect to themovement of the piston therein. The position of the rotating disc 18 mayalso be varied under different conditions of engine operation.

The structure of the pulsing unit may be modified in various ways as maybe desired for a particular applicat'ion. The coils can be wounddirectly on a permanent magnet rather than on pole pieces. Alternately,the teeth of the rotating discs can be formed by permanent magnetshaving alternative polarity, and in such case a magnet is not requiredin the magnetic structure for the coils. Electromagnets may be usedinstead of permanent magnets, and if desired a larger number of pickupcoils may be provided to increase the voltage produced by the pulsingunit. The use of more economical transistors for a given output voltageis possible because the interstage transformer increases the breakdowncapability of the output transistor by applying reverse bias thereto.

One alternate form of pulsing unit is illustrated in FIG.

4. In this unit the magnetic structure includes a permanent magnet 45supported by pole pieces 46 and 47, with the pole piece 47 having aninturned end 48 about which coil 50 is positioned. The magneticstructure is supported on a plate 51 which may be constructed like theplate which supports the contact points in a standard ignition system. Arotating member 52 is provided having teeth 53 with angle portions 54which pass between the pole piece 46 and the end 48 of the pole piece47.When a tooth 54 is positioned between the pole pieces, as shown in FIG.4, the flux from the permanent magnet 45 through coil 50 will be amaximum, as the air gap between the pole piece 46 and the end 48 of thepole piece 47 is a minimum. However, when the member 52 rotates and theangle tooth portion 54 is clear of the pole pieces, the flux through thecoil 50 will be minimum. The change in flux through the coil 50 willdevelop a voltage therein which will vary in accordance with curve A ofFIG. 3. The unit of FIG. 4 may therefore be used in the circuit of FIG.1 to provide the action as has previously been described. A movable arm36 is provided to shift the position of the magnetic structure withrespect to the rotating member 52 to advance or retard the pulse.

FIG. 5 shows a circuit generally similar to the circuit of FIG. 1, andillustrates variations which may be made in this circuit. In FIG. 5resistors 29 and 30 form a voltage divider for providing a bias voltagefor the base electrode of transistor 28. This may be advantageous whentransistors having particular characteristics are used. The circuit ofFIG. 5 also has a feedback circuit including resistor 35 connected fromthe collector electrode of tran sistor 28 to the base electrode oftransistor 20. This may be effective in improving the switching actionof the transistors.

FIG. 6 shows a further circuit embodiment which may be utilized. Amagnetic pulsing unit as previously described may be used, with the coil16 producing a voltage having a wave form as shown by curve A in FIG. 3.This voltage is applied between the base and emitter electrodes oftransistor 60 of the first stage. The transistor 60 is connected in agrounded collector circuit, with bias being applied to the emitterelectrode through the primary winding of transformer 61. Resistor 62controls the bias to the base electrode and may be a positivetemperature coefiicient thermistor as previously described. The outputsignal from transistor 60 is applied by transformer 61 between the baseand emitter electrodes of transistor 65. This transistor is alsoconnected as a grounded collector stage with the ouput being derivedfrom the emitter electrode through transformer 66. The secondary Windingof transformer 66 provides the high voltage to the distributor.

It will be apparent that various other circuit configurations can alsobe used. For example, the first stage may include a transistor with theoutput being derived from the collector electrode thereof as shown inFIGS. 1 and 5, and the second stage may be connected as a groundedcollector stage as shown by the stage including transistor 65 in FIG. 6.

The ignition system described has been found to be highly effective toprovide the ignition voltage required in modern engines. It has beenfound that a higher volt age may be provided than in systems nowcommercially used. The voltage may be maintained at a satisfactory levelfor high speed operation, and may be held at substantially constantvalue through a range of temperatures. The interstage transformerisolates the two transistors so that any non-linear characteristics inthe first stage are not amplified by the second stage. This improveshigh temperature operation and prevents runaway. Because the base andemitter electrodes of transistor 28 are coupled directly across thesecondary winding of transformer 25,

the low resistance therebetween greatly enhances stability of operation.The structure is constructed so that it may be used in presentdistributor structures to provide advance and retard action, as neededin internal combustion engines which operate at variable speed.

The ignition system has no contact points which must be replaced and nohigh voltage condenser which is subject to failure. Accordingly, themaintenance of the ignition system will be substantially less than inignition systems which depend on contact points and a condenser toprovide the high voltage. This results in a substantial overall savingin cost during the life of the engine with which the ignition system isused.

We claim:

1. An ignition system for an internal combustion engine having aplurality of ignition means and a distributor coupled to the engine andselectively applying a single high voltage pulse to successive ones ofthe ignition means, said system including in combination, pulseproducing means operating to produce control pulses in synchronism withthe internal combustion engine, a transistor stage having a transistorwith varying regions of reverse breakdown capability according to theamount of reverse bias applied thereto, said transistor stage havinginput and output circuits and including bias means for normally holdingsaid transistor cut olf, input circuit means including first transformmeans connected to said input circuit of said transistor stage forapplying control pulses thereto from said pulse producing means forrendering said transistor stage conductive, said first trans formermeans operating at the termination of each pulse from said pulseproducing means to apply a potential to said input circuit of saidtransistor stage to reverse bias said transistor to cut off and beyondcut off into a region of increased breakdown capability so that saidtransistor can withstand substantial reverse voltage applied thereto,and second transformer means including a primary winding coupled to saidoutput circuit of said transistor stage and a secondary winding coupledto the distributor, said second transformer means providing voltagestep-up of said primary winding to said secondary winding, said primarywinding being responsive to cut off of said transistor stage to developa single high voltage pulse which is stepped up in said secondarywinding and applied to the distributor.

2. An ignition system for an internal combustion engine having aplurality of ignition means and a distributor coupled to the engine andselectively applying a single high voltage firing a pulse to theignition means, said system including in combination, pulse producingmeans operating to produce pulses in synchronism with the internalcombustion engine, a first transistor connected to said pulse producingmeans and being conductive in response to each pulse received therefromto produce a direct current pulse, a second transistor and input andoutput circuits therefor, bias means for normally holding said secondtransistor cut off, first transformer means connecting said inputcircuit of said second transistor to said first transistor whereby eachpulse produced in said first transformer means by said first transistoris applied to said second transistor and causes the same to conduct,said first transformer means applying a potential to said secondtransistor at the termination of each pulse to drive said secondtransistor to cut off and beyond cut off, and second transformer meansincluding a primary winding coupled to said output circuit of saidsecond transistor and a secondary winding coupled to the distributor,said primary winding developing a sharp pulse therein in response to cutoff of said second transistor, said second transformer means providingvoltage step-up from said primary winding to said secondary winding forapplying a high voltage pulse to the distributor.

3. An ignition system for an internal combustion engine having aplurality of cylinders with ignition means, and a distributor coupled tothe engine and applying high voltage firing pulses in turn to theignition means of the cylinders thereof, said system including incombination, pulse producing means, a first transistor stage biasednormally conductive, said first transistor stage being connected to saidcoil means and being cut off in response to each pulse receivedtherefrom, a second transistor stage having input and output circuitsand including biasing means for normally holding said second transistorstage cut off, first transformer means connecting said input circuit ofsaid second transistor stage to said first transistor stage and applyinga single pulse to said second transistor stage to cause the same toconduct in response to cut off of said first transistor stage, saidfirst transformer applying a potential to said second transistor stageat the termination of each pulse to cut off said second transistorstage, and second transformer means including a primary winding coupledto said output circuit of said second transistor stage to develop asharp pulse in response to cut off of said second transistor stage, saidsecond transformer means having a secondary winding and providingvoltage step-up from said primary winding to said secondary winding forapplying a high voltage pulse to the distributor.

4. An ignition system for an internal combustion engine having aplurality of cylinders with ignition means, and a distributor coupled tothe engine and applying firing signals in turn to the ignition means ofthe cylinder thereof, said system including in combination, pulseproducing means including coil means and a magnet structure forproducing a field in said coil means, and a rotary disc of magneticmaterial having projections spaced about the outer edge thereof, andpositioned for movement adjacent said magnet structure, means coupled tothe engine for rotating said disc, a first transistor having base,emitter and collector electrodes, biasing means coupled to saidtransistor electrodes for normally holding said transistor conducting,means connecting said coil means to said base electrode, a secondtransistor having base, emitter and collector electrodes, biasing meanscoupled to said electrodes of said second transistor for normallyholding the same cut off, means coupling said base electrode of saidsecond transistor to said collector electrode of said first transistor,transformer means including a primary winding coupled to said collectorelectrode of said second transistor and a secondary winding coupled tothe distributor, and feedback resistor means connecting said collectorelectrode of said second transistor to said base electrode of said firsttransistor, said transformer providing voltage stepup from said primarywinding to said secondary winding, whereby movement of said projectionsof said disc with respect to said magnet structure produces pulses insaid coil means which are applied to said first transistor to cause thesame to be intermittently cut off, and pulses from said first transistorare applied to said second transistor to cause the same to conduct andthen be cut off, and cut off of said second transistor produces highvoltage pulses in said primary winding which are stepped up in saidsecondary winding and applied thereby to the distributor.

5. An ignition system for applying high voltage pulses to ignition meansfor igniting a combustion mixture in a combustion chamber, said systemincluding in combination pulse producing means, a first transistor stagehaving input and output circuits and including biasing means fornormally holding said stage conducting, said biasing means includingtemperature compensation means, means connecting said pulse producingmeans to said input circuit to apply pulses to said first stage, asecond transistor stage having input and output circuits and includingbiasing means for normally holding said second transistor stage cut olf,means connecting said input circuit of said second transistor stage tosaid output circuit of said first transistor stage, and transformermeans including a primary winding coupled to said output circuit of saidsecond transistor stage and a secondary winding coupled to the ignitionmeans, said transformer providing voltage step-up from said primarywinding to said secondary winding, whereby pulses applied to said firsttransistor stage causes the same to be intermittently cut off, andpulses from 'said first transistor stage are applied to said secondtransistor stage to cause the same to conduct and then be cut off, andconduction of said second transistor stage produces high voltage pulsesin said primary winding which are stepped up in said secondary windingand applied to the ignition means to ignite the mixture in thecombustion chamber.

6. An ignition system for an internal combustion engine having aplurality of cylinders with ignition means, and a distributor coupled tothe engine and applying high voltage firing pulses in turn to theignition means of the cylinders thereof, said system including incombination, pulse producing means including coil means and a magnetstructure for producing a field in said coil means, said magneticstructure including a rotary member coupled to the engine for changingthe field through said coil means to produce voltage pulses therein, afirst transistor having input and output electrodes, means connectingsaid coil means to said input electrode, a second transistor havinginput and output electrodes, means coupling said input electrode of saidsecond transistor to said output electrode of said first transistor,transformer means including a primary winding coupled to said outputelectrode of said second transistor and a secondary winding coupled tothe distributor, said transformer providing voltage step-up from saidprimary winding to said secondary winding, and circuit means connected.to said electrodes of said transistors and providing bias to said firsttransistor for normally holding the same conducting, said circuit meansproviding bias to said second transistor for normally holding the samecut off, said circuit means including means providing feedback from saidsecond transistor to said first transistor and providing temperaturecompensation whereby said first transistor is rendered more stable, withmovement of said rotary member of said magnet structure producing pulsesin said coil means which are applied to said first transistor to causethe same to be intermittently cut off, and said first transistorapplying pulses to said second transistor to cause the same to conductand then be cut off, and with the cut off of said second transistorproducing high voltage pulses in said primary winding which are steppedup in said secondary winding and applied to the distributor.

7. An ignition system for an internal combustion engine having aplurality of cylinders with ignition means, and a distributor coupled tothe engine and applying high voltage firing pulses in turn to theignition means of the cylinders thereof, said system including incombination, pulse producing means including a portion coupled to theengine for operating said pulse producing means to produce voltagepulses, a first transformer having primary and secondary windings withsaid primary Winding being connected to said pulse producing means, atransistor having base, emitter and collector electrodes with said baseand emitter electrodes being connected directly across said secondarywinding, said first transformer operating at the termination of eachpulse from said pulse producing means to apply a potential to saidtransistor to drive said transistor to cut off and beyond cut off, and asecond transformer including a primary winding coupled to said collectorelectrode of said transistor and a secondary winding coupled to thedistributor, said second transformer providing voltage step up from saidprimary winding thereof to said secondary winding thereof, said primarywinding of said second transistor developing high voltage pulses whensaid transistor is cut off which are stepped up in said secondarywinding of said second transistor and applied to the distributor.

8. An ignition system for supplying a single high voltage pulses to anignition device for igniting a combustible mixture in the combustionchamber of an internal combustion engine, said system including incombination, a first transistor stage having input and output circuitsand including biasing means for normally holding said stage conducting,means connected to said input circuit to cut off said first stage intimed relation with the internal combustion engine, a second transistorstage having input and output circuits and including biasing means fornormally holding said second transistor stage substantially entirely cutoff, means connecting said output circuit of said first transistor stageto said input circuit of said second transistor stage to render saidsecond transistor stage substantially fully conductive when said firsttransistor stage is cut oil? and to apply a reverse bias to said secondtransistor stage when said first transistor stage conducts to drive saidsecond transistor stage beyond cut off, and transformer means includinga primary Winding coupled to said output circuit of said secondtransistor stage and a secondary winding coupled to the ignition device,said transformer providing voltage stepup from said primary Winding tosaid secondary winding, whereby cut off of said second transistor stagewhen substantially fully conducting causes a single high voltage pulseto be produced in said secondary winding for application to the ignitiondevice to ignite the combustible mixture in the combustion chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,953,719 9/60Guiot 123148 2,981,865 4/61 Fernbach 315209 RICHARD B. WILKINSON,Primary Examiner.

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE HAVING APLURALITY OF IGNITION MEANS AND A DISTRIBUTOR COUPLED TO THE ENGINE ANDSELECTIVELY APPLYING A SINGLE HIGH VOLTAGE PULSE TO SUCCESSIVE ONES OFTHE IGNITION MEANS, SAID SYSTEM INCLUDING IN COMBINATION, PULSEPRODUCING MEANS OPERATING TO PRODUCE CONTROL PULSES IN SYNCHRONISM WITHTHE INTERNAL COMBUSTION ENGINE, A TRANSISTOR STAGE HAVING A TRANSISTORWITH VARYING REGIONS OF REVERSE BREAKDOWN CAPABILITY ACCORDING TO THEAMOUNT OF REVERS BIAS APPLIED THERETO, SAID TRANSISTOR STAGE HAVINGINPUT AND OUTPUT CIRCUITS AND INCLUDING BIAS MEANS FOR NORMALLY HOLDINGSAID TRANSISTOR CUT OFF, INPUT CIRCUIT MEANS INCLUDING FIRST TRANSFORMMEANS CONNECTED TO SAID INPUT CIRCUIT OF SAID TRANSISTOR STAGE FORAPPLYING CONTROL PULSES THERETO FROM SAID PULSE PRODUCING MEANS FORRENDERING SAID TRANSISTOR STAGE CONDUCTIVE, SAID FIRST TRANSFORMER MEANSOPERATING AT THE TERMINATION OF EACH PULSE FROM SAID PULSE PRODUCINGMEANS TO APPLY A POTENTIAL TO SAID INPUT CIRCUIT OF SAID TRANSISTORSTAGE TO REVERSE BIAS SAID TRANSISTOR TO CUT OFF AND BEYOND CUT OFF INTOA REGION OF INCREASED BREAKDOWN CAPABILITY SO THAT SAID TRANSISTOR CANWITHSTAND SUBSTANTIAL REVERSE VOLTAGE APPLIED THERETO, AND SECONDTRANSFORMER MEANS INCLUDING A PRIMARY WINDING COUPLED TO SAID OUTPUTCIRCUIT OF SAID TRANSISTOR STAGE AND A SECONDARY WINDING COUPLED TO THEDISTRIBUTOR, SAID SECOND TRANSFORMER MEANS PROVIDING VOLTAGE STEP-UP OFSAID PRIMARY WINDING TO SAID SECONDARY WINDING, SAID PRIMARY WINDINGBEING RESPONSIVE TO CUT OFF OF SAID TRANSISTOR STAGE TO DEVELOP A SINGLEHIGH VOLTAGE PULSE WHICH IS STEPPED UP IN SAID SECONDARY WINDING ANDAPPLIED TO THE DISTRIBUTOR.